The present invention relates to an apparatus and method for audio signal envelope encoding, processing and decoding and, in particular, to an apparatus and method for audio signal envelope encoding, processing and decoding employing distribution quantization and coding.
Linear predictive coding (LPC) is a classic tool for modeling the spectral envelope of the core bandwidth in speech codecs. The most common domain for quantizing LPC models is the line spectrum frequency (LSF) domain. It is based on a decomposition of the LPC polynomial into two polynomials, whose roots are on the unit circle, such that they can be described by their angles or frequencies only.